This invention relates broadly to buckle-type sheet folding machines and more particularly to mechanisms for adjusting paper stops in fold pans of buckle-type sheet folding machines.
Stated briefly, a buckle-type folding machine normally comprises a series of rollers and fold-pan assemblies. A sheet of paper to be folded is inserted between two rotating rollers of a first roller set and is driven by these two rollers into a fold pan of a fold-pan assembly. A forward edge of the sheet eventually strikes a paper stop in the fold-pan; however, the two rollers continue to feed the sheet forward. Thus, the sheet buckles and the bulge of this buckle eventually extends between two rollers of a second roller set. These rollers fold the sheet at the bulge and feed this folded edge into a second fold pan of a second fold pan assembly. Upon striking a second paper stop there is a new buckle in the sheet and this buckle is, in turn, inserted between two rollers of a third roller set. This process continues until the sheet is folded a desired number of times.
In most buckle-type folding machines the paper stops of the fold pan assemblies are adjustable so that the positions of folds on sheets can be controlled.
In most prior art sheet folding apparatus it is difficult to accurately adjust the positions of paper stops, and, in some prior art devices, it is actually necessary to remove the fold pan assemblies in order to adjust their positions.
U.S. Pat. No. 3,495,818 to Marian describes a sheet folding apparatus wherein paper stops can be adjusted relatively easily by means of negator springs. In this device, two sets of springs are wound on a single shaft for each paper stop. Extensions of one set of the springs are attached directly to a front side of the paper stop and extensions of the other spring set extend around pulleys and are attached to the back side paper stop. With this arrangement the two sets of springs tend to oppose one another and balance the position of the paper stop. To change the position of the paper stop the shaft is rotated.
Marian's device, however, requires a relatively large amount of space and is somewhat complicated in structure. It is therefore an object of this invention to provide an adjusting apparatus for paper stops which is accurate and convenient to use, but yet is relatively small and uncomplicated.
The adjusting mechanisms of some prior-art devices include indicating means for indicating the positions of adjustable paper stops. Some of these indicating devices are inaccurate and some of them are difficult to read. It is therefore yet another object of this invention to provide an indicating device for a paper stop adjusting means which is accurate and relatively easy to read.
Another problem which exists in the prior art is that of making folds on sheets which are perpendicular or parallel with printed material on the sheets. Normally, paper stops are perpendicular with longitudinal axes of fold pans so that sheet edges registered by paper stops are also perpendicular with longitudinal axes of the fold pans. The resulting folds of such sheets are parallel with these registered edges. However, it is often the case that printed material on sheets is not perpendicular or parallel with the sheets' edges. It is, therefore, sometimes desirable to register the sheets at slight angles relative to the fold pans' longitudinal axes so that folds can be made square with the printed material. Thus, it is yet another object of this invention to provide a paper-stop adjusting means which can be used to position a paper stop at an angle relative to a fold pan's longitudinal axis.